PROJECT SUMMARY/ABSTRACT Technologies related to the management of type 1 diabetes (T1D) have been advancing rapidly and have the potential to improve health outcomes. Real-time continuous blood glucose monitoring (CGM) is one such technology. CGM provides nearly continuous data on glucose variability, indicates direction and rate of change of glucose concentrations, and can alert the user to impending or actual hypoglycemia and hyperglycemia. While CGM leads to improved glycemic control with near-daily use in children and adolescents, they are less likely to use CGM consistently compared to adults. Prior research has, in general, failed to identify factors that predict CGM adherence in youth over time. The identification of such factors is critical for the development of interventions to increase long-term use of CGM and related emerging technologies (e.g., a fully closed-loop system). The decision making process related to adding CGM to the regimen- especially the child's involvement in the decision- may lay the groundwork for effective implementation and management of CGM but is not well-understood. Children's decision making involvement has been hypothesized to enhance self-efficacy and increase satisfaction with medical care and cooperation with treatment. Intervening at the time of the decision about whether or not to add CGM to the youth's treatment regimen has the potential to impact the trajectory of CGM use and may be more effective than waiting until problems develop. The primary objectives of this mixed methods research proposal are to identify and describe patterns of decision making related to adding CGM to the treatment regimen for youth with T1D and test the hypothesis that children's involvement in the decision to start CGM will impact CGM satisfaction, CGM self-efficacy, and CGM use. We will enroll, assess, and interview youth with T1D ages 8-17 years within two weeks of the decision to add CGM to their regimen, conduct follow-up assessments and interviews 2 months after CGM initiation, and download CGM use data 3 months after CGM initiation. We will utilize semi- structured interviews with children and parents at baseline and follow-up to explore the decision making process about CGM, experiences with CGM, and suggestions for specific actions that providers, parents, and youth can take to improve the decision making process, facilitate youth involvement, and maintain CGM use over time. We will also use the quantitative data regarding CGM use to categorize participants into near-daily users versus intermittent and non-users and determine whether decision making themes differ between these groups. The next step of our research agenda will be a randomized controlled trial to test an intervention to enhance children's involvement in the decision about CGM, prevent declines in CGM use that are typically seen in youth with T1D, and maximize the clinical benefits that can be obtained by appropriate use of this important and costly new technology.